House doors were locked Thursday night as lawmakers prepared for their first closed session in 25 years to debate surveillance legislation.

Republicans requested privacy for what they termed "an honest debate" on the new Democratic eavesdropping bill that is opposed by the White House and most Republicans in Congress.

The private session was scheduled for nighttime so the House chamber could be swept by security personnel to make sure there were no listening or recording devices.

The last such session in the House was in 1983 on U.S. support for paramilitary operations in Nicaragua. Only five closed sessions have taken place in the House since 1825.

Many Democrats initially objected, calling it a political ploy by Republicans to delay the vote. Indeed, it did: House leaders pushed off the scheduled vote until Friday, just before taking a two-week recess. If passed, the bill would have to be approved by the Senate.

President Bush vowed to veto the House Democrats' version of the terrorist surveillance bill, saying it would undermine the nation's security.